This invention pertains to devices for measuring angles in a small sized instrument and, in particular, to an inclined plate 360 degree absolute angle sensor for use in biomedical, industrial, commercial and personal applications, such as measuring the angles of various body joints or the angles of implants or bones taken from radiographic images.
There have been a number of attempts to develop angle measuring units. Examples of this type device are the United States Patent issued to Graham, Baillet and Sankey U.S. Pat. No. 4,442,606 issued on 17 Apr. 1984 for a Digital Goniometer is an example of this typical units. Other attempts in this area include the United States Patents issued to Joyal et al, U.S. Pat. No. 3,996,670 issued on December 1976 and to Beck, U.S. Pat. No. 4,249,314 issued in February 1981. There are, however many difficulties with those type devices. Among the difficulties are moisture problems, problems created by dirt and limitations of visibility and motion. Potentiometers wear out over time, usually have a travel stop which limits their rotatability and are not transparent.
What is needed is an inclined plate 360 degree absolute angle sensor that does not wear out over time and has an unlimited 360 degree resolution. What is needed is an assembly which is simple and easy to use, has a complete range of motion and allows complete visibility for the operator to measure any desired angle. What is also needed is signal sending means that allows the data from the sensors to be processed by a micro controller or personal computer.
It is the object of this invention to teach an inclined plate 360 degree absolute angle sensor which avoids the disadvantages and limitations, recited above in similar systems. Another object of this invention is to provide a system that is extremely efficient and accurate.